This invention relates generallly to injection molded plastic parts such as the inlet or outlet portion of an automobile radiator which includes one or more tubular portions on which the hoses for circulating coolant through the radiator are mounted; and more particularly to the molding of such a part so that the roundness of the tubular portions are maintained. The present invention is thus an improvement on the invention disclosed in U.S. Pat. No. 4,709,757 assigned to the assignee of this application. Prior to the invention in U.S. Pat. No. 4,709,757, such parts were molded utilizing mold sections that are moved toward and away from each other resulting in a parting line between the mold sections. The result is a formation of "flash/mismatch" on the tubular portions of the radiator part on which the hoses are mounted. Flash results from the plastic being molded coming out between the parting lines of the mold, and mismatch is excess plastic on the molded part resulting from mold parts which are not in exact alignment. The result is undesirable and excess plastic on the molded part which is herein referred to as "flash/mismatch".
During use of the mold, the resulting flash/mismatch becomes increasingly significant and the molded parts become more and more prone to leakage when hoses are mounted thereon. The result is an unsatisfactory situation from the standpoint of keeping the hoses mounted on the radiator part without damage or leakage in this area.
The invention in U.S. Pat. No. 4,709,757 provides an improved method for forming parts of this type in which the parting lines on the tubular portions are avoided to thereby avoid the possibility of damage or leakage in this area. The present invention has this advantage and in addition insures the roundness of the tubular portions.